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Comparative Study
. 2019 Sep 20:14:2135-2144.
doi: 10.2147/COPD.S203715. eCollection 2019.

Impact of symptom variability on clinical outcomes in COPD: analysis of a longitudinal cohort

Mi-Ae Kim  1 , Min-Kang Suh  1 , Jisoo Park  1 , Jung-Hyun Kim  1 , Tae-Hoon Kim  1 , Eun Kyung Kim  1 , Yeon-Mok Oh  2 , Sang-Do Lee  2 , Ji-Hyun Lee  1
Affiliations
Comparative Study

Impact of symptom variability on clinical outcomes in COPD: analysis of a longitudinal cohort

Mi-Ae Kim et al. Int J Chron Obstruct Pulmon Dis. .

Abstract

Purpose: We compared clinical characteristics of COPD patients according to symptom variability and evaluated the effect of symptom variability during the first year of enrollment on clinical outcomes of COPD.

Methods: We analyzed COPD patients' data from the Korean Obstructive Lung Disease (KOLD) cohort. Symptom variability was defined based on the value of standard deviation (SD) of mMRC scores obtained every 3 months during the follow-up period of the first year. Patients were divided into 2 groups: the consistent (SD of mMRC scores =0) and variable (SD of mMRC scores >0) groups. Clinical characteristics and outcomes were compared in terms of symptom variability.

Results: A total of 407 patients were included in the analysis. Patient age was 67.2 years and 97.8% of the subjects were male. Initial mMRC was 1.5 and the SD of mMRC scores during the first year was 0.5. There were 137 subjects (33.7%) in the consistent group and 270 (66.3%) in the variable group. The variable group showed a lower FEV1 (P=0.019) and a higher mMRC score (P=0.001). The annual incidence of acute exacerbation of COPD (AE-COPD) tended to be higher in the variable group (P=0.078) and that of severe AE-COPD was higher in the variable group than in the consistent group (P=0.002). The variable group showed a higher proportion of annual exacerbators (P=0.001) and frequent exacerbators (P=0.017). In multivariate logistic regression analysis, the variable group was significantly associated with annual exacerbators (OR =1.963, P=0.011) and frequent exacerbators (OR =2.090, P=0.055).

Conclusion: COPD patients with symptom variability may have higher exacerbation risk as well as lower lung function and more severe respiratory symptoms.

Keywords: COPD; death; exacerbation; lung function; symptom; variability.

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Conflict of interest statement

The authors report no conflicts of interest in this work.

Figures

Figure 1
Figure 1
The annual incidence of exacerbations according to symptom variability: the annual incidence of AE-COPD (A) and the annual incidence of severe AE-COPD (B). The variable group tended to show higher incidences of AE-COPD per year (A) and severe AE-COPD per year (B) when compared to the consistent group. *Highly suspected outliers; osuspected outliers. Abbreviation: AE-COPD, acute exacerbation of chronic obstructive pulmonary disease.
Figure 2
Figure 2
The proportion of annual exacerbators (A) and frequent exacerbators (B) according to symptom variability. The variable group showed higher proportions of annual exacerbators (A) and more frequent exacerbators (B) compared to the consistent group. Abbreviations: Annual exacerbator, AE-COPD/year ≥1; frequent exacerbator, AE-COPD/year ≥2 or severe AE-COPD/year ≥1.
See this image and copyright information in PMC

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